Conveyor belt tensioning and tracking systems

ABSTRACT

A tensioning and tracking system with specific useful features for adjusting a conveyor belt is disclosed. Generally, the tensioning and tracking systems include a pair of plate members attached together and defining a channel and an elongated opening. Mounted within the channel is a slide plate having a distal end. Also, connected to one of the side plate members is a rotating member for reciprocally advancing the distal end of the slide plate into the elongated opening. The position of the slide plate within the elongated opening is secured by a locking screw connected to one of the plate members.

This Application is a continuation of co-pending prior U.S. applicationSer. No. 09/235,772 filed Jan. 22, 1999.

DESCRIPTION

1.Technical Field

The present invention generally relates to systems for adjusting thetension and tracking of an endless belt, and in particular to systemsthat provide for easy and quick adjustments.

2. Background Art

In many conveyors available today, belt tensioning and trackingmechanisms are combined by journaling the ends of a pulley in blocksthat are slidably mounted to the conveyor's frame. Accordingly, thesemechanisms provide for adjustments to the tension and tracking of theconveyor belt by adjusting the position of the slide blocks. However, inmechanisms of this type, an adjustment to the belt tracking effects thetensioning, and vice versa. Accordingly, trained personnel are requiredfor properly adjusting the belt's tension and tracking.

Moreover, many conveyors are used in applications wherein, if the lengthof the conveyor is changed, then other automated production equipmentconnected to the conveyor must also be repositioned to accommodate thechange in length. In addition, after each adjustment to the conveyorbelt, many tensioning and tracking mechanisms require that an excessivenumber of bolts and screws be tightened for securing the position of theconveyor's pulleys.

Also, few conveyors provide for easy removal and replacement of the beltduring maintenance. Instead, many conveyors require a time consumingprocess wherein several parts must be removed before the belt.

Hence, the present invention overcomes the above discussed deficienciesof the prior art.

SUMMARY OF THE INVENTION

Generally, the tensioning and tracking systems of the present inventioninclude a pair of plate members attached together and defining a channeland an elongated opening. Mounted within the channel is a slide platehaving a distal end. Also, connected to one of the side plate members isa rotating member for reciprocally advancing the distal end of the slideplate within the elongated opening. The position of the slide platebeing secured by a locking screw connected to one of the plate members.

Other advantages and features of the present invention will be apparentfrom the following description of specific embodiments illustrated inthe accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a fragmentary top perspective view, partially in phantom, of aconveyor having tensioning and tracking systems in accordance with thepresent invention;

FIG. 2 is a top perspective view of the tensioning system shown in FIG.1;

FIG. 3 is a top view, partially in phantom, of the tensioning systemdepicted in FIG. 1 having a pair of tensioning assemblies attached to apair of connecting blocks;

FIG. 4 is a perspective view of one tensioning assembly removed from theconveyor of FIG. 1;

FIG. 5 is a perspective view, partially in phantom, of the othertensioning assembly removed from the conveyor of FIG. 1;

FIG. 6 is a perspective view of one tracking assembly within thetracking system of FIG. 1;

FIG. 7 is a perspective view, partially in phantom, of the othertracking assembly within the tracking system of FIG. 1;

FIG. 8 is an assembly view of the tracking assembly of FIG. 6;

FIG. 9 is an exploded side view of the pulley rotatably connected to thetensioning assemblies of FIG. 1;

FIG. 10 is a cross-sectional view the pulley rotatably connected to thetracking assemblies of FIG. 1;

FIG. 11 is a cross-sectional view of the tracking assembly of FIG. 7;

FIG. 12 is a cross-sectional view of an alternative embodiment of thetracking assemblies of FIG. 1;

FIG. 13 is a top view, partially in phantom, of an alternativeembodiment of the tensioning assemblies of FIG. 1;

FIG. 14 is a fragmentary view of yet another alternative embodiment ofthe tensioning assemblies of FIG. 1, having a clip for receiving thethumb wheel; and

FIG. 15 is a perspective view of the clip depicted in FIG. 14.

DETAILED DESCRIPTION

While this invention is susceptible of embodiments in many differentforms, there is shown in the drawings and will herein be described indetail preferred embodiments of the invention. The present disclosure isto be considered as an exemplification of the principles of theinvention and is not intended to limit the broad aspects of theinvention to the embodiments illustrated.

Referring now to the drawings, and particularly to FIG. 1, a conveyor 10is depicted having an elongated frame 12. Attached to the ends 14 and 16of the frame 12 is a belt tensioning system 18 and a belt trackingsystem 20, respectively.

Preferably, the frame 12 is defined by a pair of spaced parallel siderails 22 formed of extruded aluminum. The side rails 22 are similar toeach other and include an outer face 24 and an inner face 25. The outerface 24 of each rail 22 has a longitudinal slot 26 extending the rail'slength. The slot 26 is bordered by an upper lip 28 and a lower lip 30.The slot 26 projects within a convex beam portion 31 protruding from theinner face 25 and extending the length of the rail 22. Furthermore, thelongitudinal edges of each rail 22 include a pair of parallellongitudinal flanges 32 extending perpendicularly from face 24.

Mounted between the side rails 22 are one or more spares 36 and a bedplate 38 having an upper planar surface 39. The spares 36 providesupport for the bed plate 38. The spares 36 are preferably formed ofaluminum or an aluminum alloy and are attached to the beam portions 31of the side rails 22 by screws or the like received within tapped holesin the ends of each spare. Furthermore, bed plate 38 tightly fitsbetween the rails 22 and is attached by bolts to the spares 36.

As explained in detail further herein, mounted to the belt tensioningsystem 18 and the belt tracking system 20 are a pair of pulleyassemblies 40 and 41, respectively. Preferably, 40 is an idler pulleyassembly and 41 is a drive pulley assembly. Trained over the pulleys 40,41 is an endless conveyor belt 42 with a portion of the belt laying onthe upper support surface 39 of the bed plate 38.

A power source 44 is operably connected to the drive pulley 41 forrotating the conveyor belt 42. The power source 44 can comprise of, forexample, an electric motor connected to the drive pulley 41 by a drivebelt (not shown) and protected by a cover 46.

Turning to FIGS. 2-5, and as indicated above, the belt tensioning system18 is mounted to one end of the conveyor 10. The belt tensioning system18 includes a pair of tensioning assemblies 48 having a fixed pair ofconnecting blocks 50 along with pulley assembly 40 mounted therebetween.The tensioning system 18 provides for selectively positioning the pulley40 along the longitudinal axis of the conveyor 10 defined by theconveyor side rails 22.

As shown in the FIGURES, and particularly FIGS. 4 and 5, each tensioningassembly 48 includes an outer plate member 52 and an adjoining co-planarinner plate member 54 made of aluminum, stainless steel, or other likematerial. The outer perimeter dimensions of the plate members 52, 54 aresubstantially the same except the length of the inner plate 54 isshorter than the outer plate 52. Both plate members 52,54 preferablyhave two horizontal walls, two vertical walls, and a beveled end wall 55to facilitate removal and installation of the conveyor belt. Moreover,each plate member 52,54 has a planer outer surface and a co-planer innersurface 56.

The plate members 52,54 of each belt tensioning assembly 48 are attachedto one of the side rails 22 wherein a portion of the outer plate member52 adjoins against the rail's outer face 24. In addition, the planarvertical end wall 57 of each belt tensioning assembly inner plate member54 adjoins against the planar terminal end surface of a respective rail22 for providing stability of the tensioning assembly. Likewise, theinner surface of the outer plate 52 can include at least one groove 58(FIG. 8) for receiving and adjoining against one of the rail'slongitudinal flanges 32. The outer plate member 52 is bolted onto therail 22 wherein, preferably, nuts or a block (not shown) are receivedwithin the slot 26 and engage the slot's upper and lower lips 28,30during tightening of the bolts.

Extending through both plate members 52,54 is a generally rectangularopening 62 and an elongated opening 64. Preferably, when the plates52,54 are attached together by screws, rivets or similar means, therectangular openings 62 within the plates are aligned to provide awindow 66 extending through each tensioning assembly 48. Similarly, theelongated openings 64 within each plate member 52,54 are also aligned toprovide an open guide slot 68 through each tensioning assembly 48. Eachguide slot 68 preferably has two parallel sides 69 and two arcuate ends70 for limiting the travel of the pulley assembly 40 and thusmaintaining the pulley within the slot even when the belt is removed.

As shown in FIGS. 3, 4 and 5, defined within the inner surface 56 ofouter plate 52 is a channel 72 extending about the rectangular opening62 and the elongated opening 64 of the outer plate. The channel 72 hasan enlarged portion 74 about the rectangular opening 62 and a passage 76extending from the enlarged portion 74 of the channel 72 and along thesides of the elongated opening 64. The passage 76 has two longitudinalside walls 77,78 in parallel spaced relationship to each other withopening 64 therebetween. Accordingly, a pair of spaced parallel lips80,81 are provided about the opening 64 in the outer plate member 52.

Channel 72 receives a generally L-shaped slide plate 82 having a thumbwheel cooperating portion 84 and a beam portion 86 integrally connectedto each other. The cooperating portion 84 is generally rectangular andis dimensioned to fit, and longitudinally side, within the enlargedportion 74 of the channel 72. Likewise, the beam portion 86 of the slideplate 82 slidingly engages the side walls 78,80 of the channel passage76. Accordingly, the side walls 78,80 provide lateral support of theslide plate beam portion 86 along the entire length of one side 87 ofthe plate 82 an a substantial portion of the other side 88.

The distal end 89 of the slide plate 82 opposite the thumb wheelcooperating portion 84 is concave. The slide plate 82 is longitudinallymoveable within channel 72 for adjustably positioning its distal end 89within the elongated opening 64 of the tensioning assembly 48. The slideplate 82 is dimensioned to slide within the elongated portion 74 of thechannel 72 and against the inner surface of the inner plate 54.Accordingly, the elongated portion 74 of the channel 72 and the innersurface of the inner plate 54 define a cavity wherein only longitudinalmovement of the slide plate 82 is permitted.

FIGS. 2 and 3 depict the connecting blocks 50 attached to the tensioningassemblies 48. Preferably, each connecting block 50 is attached byscrews or the like to the inner plate 54 of a respective tensioningassembly 48. Likewise, the connecting blocks 50 are attached to eachother by bolts 90.

Defined within each connecting block 50 is a notch 92 that adjoins thewindow 66 of an associated tensioning assembly 48. Attached to eachblock 50 within notch 92 is a threaded shaft 94 with a rotational memberconsisting of a thumb wheel 96 rotatably coupled thereto. The shaft 94is in parallel alignment with the longitudinal axis of the conveyor 10.Moreover, a portion of the thumb wheel 96 projects through both thewindow 66 and an aperture 98 within the cooperating portion 84 of theside plate 82. Accordingly, rotation of the thumb wheel 96 provides auser with leverage in longitudinally advancing the slide bar 82 withinthe channel 72 of the respective tensioning assembly 48.

In an alternative embodiment shown in FIG. 13, each connecting block canbe substituted with a generally U-shaped block or housing 97 attached bescrews to the inner plate 54 of each tensioning assembly 48. Like theconnecting blocks, a threaded shaft 94 with a thumb wheel 96 is coupledto the housing 97. Furthermore, the two tensioning assembly housings 79within the tensioning system are attached to each other by a crossbar orspare 36.

As shown in FIGS. 14 and 15, in yet another embodiment, a U-shaped clip99 preferably made of plastic can be implemented for receiving the thumbwheel 96 of each tensioning assembly 48. The clip 99 prevents washers101 that adjoin each side of thumb wheel 96 from being chocked.

As depicted in FIG. 5, defined within the beam portion 86 of each slideplate 82 is a longitudinal slot 100 having a narrow open portion 102.Received within the narrow open portion 102 is the threaded shaft of alocking screw 104 (FIG. 3) threadingly coupled to the inner plate 54 ofthe tensioning assembly 48. The head of the locking screw 104 isaccessed through an aperture 105 in the outer plate member. The head ofthe locking screw 104 is too large to pass through the narrow openportion 102 of the slot 100. This allows for fixing the position of theslide plate 82, and in particular its distal end 88, by tightening thehead of the locking screw 104 against the planar surface of the slideplate.

As shown in FIG. 2, received within the elongated guide aperture 64 ofeach tensioning assembly 48 is a generally cylindrical sleeve 106 whichis part of the pulley assembly 40 also depicted in FIG. 9. The sleeves106 are rotatably mounted to the ends of the pulley assembly spindle 107by radial bearings located within the confines of the spindle. The outerend of each sleeve 106 includes a pair of opposed flats 108 in co-planarspaced relationship with each other. Preferably, the flats 108 extendfrom the distal end of each sleeve 106 to a distance short of thespindle 107 such that a portion 109 of the sleeve's arcuate surface istherebetween.

The flats 108 are slidingly engaged by the parallel side walls 110 ofthe elongated opening 64 in the outer plate member 52 for preventingrotation of the sleeve 106 relative to the tensioning assemblies 48.However, the portions 109 of the sleeve's arcuate surface between theflats 108 and the spindle 107 are slidingly engaged by parallel sidewalls 111 of the elongated opening 64 in the inner plate member 54.Accordingly, the spacing between the parallel walls 110 of the slotopening in the outer plate member 52 is less than the spacing betweenlike walls 111 in the inner plate 54.

The sleeve 106 is also abutted by the concave end 88 of the slide plate82. Accordingly, movement of each slide plate 82 within each tensioningassembly 48 results in like movement of one end of the pulley assembly40. Therefore, rotation of both thumb wheels 96 moves the spindle 40 fortightening the belt 42 trained over the pulley assembly 40. However,adjusting the position of the spindle 40 does not change the overalllength of the sides of the conveyor. Moreover, the slide plates 83 aresliding engaged by the lips 80,81 about the elongated openings 64 in thetensioning assemblies 48 to provide additional stability of the pulleyassembly 40.

Turning back to FIG. 1, and as indicated above, the belt tracking system20 is mounted to end 16 of the conveyor 10 opposite the belt tensioningsystem 18. The belt tracking system 20 includes a pair of trackingassemblies 112 having pulley assembly 41 therebetween. Also, if desireda spare, 36 can be attached between the tracking assemblies 112. Likethe tensioning system 18, the tracking system 20 provides forselectively positioning the pulley 41 along the longitudinal axis of theconveyor 10.

As shown in FIGS. 6-8, and similar to the tensioning assemblies 48within the tensioning system 18, each tracking assembly 112 includes anouter plate member 114 and an a co-planar inner plate member 116 thatare attached together by screws, rivets, or other like conventionalmeans. The perimeter of the plate members 114,116 are substantiallysimilar except for the inner plate 116 having a shorter length than theouter plate 114. Preferably, both plate members 114,116 also include abeveled end wall 118 for ease in removing and replacing the conveyorbelt.

Each belt tracking assembly 112 is attached to one of the side rails 22wherein a portion of the outer plate member 114 abuts the outer face 24of the rail. The outer plate member 114 to each of the belt trackingassemblies is attached to a respective side rail 22 by bolts that arethreaded onto nuts or a block (not shown) engaging the upper and lowerlips 28,30 within slot 26. Moreover, the inner plate member 116 of eachbelt tracking assembly abuts against the end surface of the rail 22.

Passing through both the outer and inner plate members 114,116 is anelongated opening 122. Moreover, a generally annular opening 120 extendsthrough the outer plate member 114. The elongated apertures 122 withineach plate 114,116 are aligned when the plates are attached together toprovide an open guide slot 124 through each tracking assembly 112. Theguide slot 124 is similar to the tensioning guide slot 68 and includestwo parallel sides 125 and two arcuate ends 126.

As depicted in FIGS. 7 and 8, within the inner surface 127 of the outerplate 114 is a channel 128 similar to the channel 72 within eachtensioning assembly. The channel has an enlarged portion 130 about theannular opening 120 and a passage 132 extending from the enlargedportion 130 of the channel 128 and along the sides 125 of the elongatedopening 122. The passage 132 has two parallel longitudinal side walls134,136 with aperture 122 located between the side walls to provide apair of spaced parallel lips 137,138.

A slide plate 139 having a proximal end 140 and a distal end 142 isreceived within the channel 128. The slide plate 139 is generallyrectangular except for distal end 142 being concave. The slide plate 139is allowed to longitudinally side within passage 132 with side walls140,141 for providing lateral support along one entire side of the slideplate and a substantial portion of the other side.

Received within the enlarged portion 130 of the channel 128 is arotating member consisting of a cam 144 having a cylindrical pivot 146projecting from one side. The pivot 146 is received by the annularopening 120 through the outer plate 114. The distal end of the pivot 146has a hexagonal socket 148 for receiving the end of an Allen wrench forrotating the cam 144 about the pivot. The outer perimeter surface 150 ofthe cam 144 abuts against the planar proximal end 152 of the slide plate139 opposite its distal end. Accordingly, the cam 144 provides a userwith leverage for moving the slide plate 139 wherein rotation of the camresults in longitudinal axial movement of the slide plate within thepassage of the tracking assembly.

As illustrated in FIGS. 8 and 11, formed within the slide plate 139 ofeach tracking assembly 112 is a longitudinal open slot having a narrowportion 162. Received within narrow portion 162 is the threaded shaft ofa locking screw 164 coupled to the inner plate of the tracking assembly112. However, the head of the locking screw 164 is too large to passthrough the narrow portion 162. Accordingly, the locking screw 164provides for adjustably fixing the position of the slide plate 139 bytightening the head of the screw against the planar surface of the slideplate wherein access to the screw is provided by opening 166 withinouter plate member 114.

As depicted in FIGS. 1 and 10, drive pulley assembly 41 is mounted tothe tensioning assemblies 112. The drive pulley assembly 41 includes agenerally cylindrical sleeve 170 rotatably mounted to one end of spindle171 and received within the elongated guide slot 124 of each trackingassembly 112. The sleeves 170 are rotatably mounted to the spindle 171with radial bearings 172 and thrust bearing 173 located in the confinesof the spindle for reducing wear. Like the idler pulley assembly 40, theouter end of each sleeve 170 is formed with a pair of opposed flats 174that are in co-planar spaced relationship to each other. However, one ofthe sleeves 170 has an open bore 176 extending along the sleeve'slongitudinal axis for receiving a bearing or a bronze bushing 182. Thebushing 182 receives a keyed shaft 178 that is operably coupled to themotor and the spindle 171 for rotation of the spindle. In an embodiment,the shaft 178 is frictionally secured to the spindle 171 by pressfitting.

Each sleeve 170 is received within the elongated guide slot 124 of anassociated tracking assembly 112 with the flats 174 being slidinglyengaged by the parallel side surfaces 125 of the elongated opening 122in the outer plate 114. Moreover, the portion of the sleeve's arcuateouter surface between the flats 174 and the spindle 171 are slidinglyengaged by parallel side surface of the opening 122 in the inner plate116.

The sleeve 170 of each tracking assembly 112 is abutted by the concaveend of an associated slide plate 130. Accordingly, movement of eachslide plate 130 within each tracking assembly 112 results in likemovement of one end of the drive pulley assembly 41. Therefore, rotationof both cams 144 moves the spindle 171 for adjusting the tracking of thebelt 42 without changing the overall length of the conveyor.

As shown in FIG. 11, a seat 184 can be provided in the channel 128 ofthe outer plate 114 about opening 120. An o-ring 186 can be receivedwithin the seat 184 and about the pivot 146 of the cam 144 forfrictionally damping rotation of the cam. Alternatively, if desired, theseat 184 can be provided by the cam 114 about the pivot 146 as shown inFIG. 12. Moreover, a length of plastic, rubber, or other like material188, such as POLYCORD, (Reinach-Basel Switzerland Corporation,Switzerland) can extend through an open bore in the cam 144 forfrictionally sliding along the surface of the channel 128.

While the specific embodiments have been illustrated and described,numerous modifications come to mind without significantly departing fromthe spirit of the invention and the scope of protection is only limitedby the scope of the accompanying claims.

What is claimed is:
 1. A device mounted to a conveyor for selectivelypositioning a pulley comprising: an assembly defining a passage and anelongated opening, the passage having a pair of parallel side walls anda pair of parallel longitudinal walls extending perpendicularly inrelation to the side walls; a slide plate slidably mounted within thepassage and having a distal end; and a thumb wheel operably connected tothe assembly for reciprocally advancing the distal end of the slideplate into the elongated opening by a select distance.
 2. The device ofclaim 1 wherein a locking device is operably connected to the assemblyfor securing the position of the distal end within the opening.
 3. Thedevice of claim 1 wherein the assembly includes a plurality of platemembers wherein at least one of the plate members adjoins an elongatedside rail of the conveyor and another one of the other plate members isattached to the side rail.
 4. The device of claim 3 wherein at least oneof the plate members defines an aperture for receiving a portion of thethumb wheel member.
 5. The device of claim 1 wherein the thumb wheel isthreadingly coupled to a shaft operably connected to at least one of theplate members.
 6. The device of claim 1 wherein the thumb wheel issandwiched between a pair of washers.
 7. The device of claim 6 whereinthe washers are received by a clip.
 8. The device of claim 1 wherein theslide plate includes a concave distal end abutting against the pulley.9. The device of claim 3 wherein at least one of the plate membersincludes a pair of lips within the channel and about the opening. 10.The device of claim 1 wherein the pulley adjoins the slide plate and anendless conveyor belt is trained over the pulley, the conveyor beltproviding an upper conveyor surface that is constant in length.
 11. Thedevice of claim 1 further including another device mounted to theconveyor for selectively and independently positioning the pulley.
 12. Adevice mounted to a conveyor for selectively positioning a pulley alonga longitudinal axis defined by a pair of side rails comprising: a pairof assemblies with each assembly attached to one of the side rails andincluding a pair of plate members attached together and defining acavity and an elongated opening, one of the plate members abuttingagainst one of the side rails and the other plate member attached to theside rail, the cavity having a pair of parallel side walls and a pair ofparallel longitudinal walls extending perpendicularly in relation to theside walls; a slide plate mounted within the cavity and having a concavedistal end abutting one end of the pulley; and a thumb wheel operablyconnected to at least one of the plate members for longitudinallyadvancing the slide plate and one end of the pulley by a selectdistance.
 13. The device of claim 12 wherein at least one of the platemembers defines an aperture for receiving a portion of the thumb wheel.14. The device claim 12 wherein the thumb wheel is threadingly coupledto a shaft operably connected to at least one of the plate members. 15.The device of claim 12 where the thumb wheel is positioned between apair of washers.
 16. The device of claim 15 wherein the washers and thethumb wheel are received by a clip.
 17. The device of claim 12 whereinthe pulley adjoins the slide plate and an endless conveyor belt istrained over the pulley, the conveyor belt providing an upper conveyorsurface that is constant in length.
 18. The device of claim 12 furtherincluding another device mounted to the conveyor for selectively andindependently positioning the pulley.
 19. A device mounted to a conveyorfor selectively positioning a pulley along a longitudinal axis definedby a pair of side rails comprising: a pair of assemblies with eachassembly attached to one of the side rails and including a pair of platemembers attached together and defining a cavity and an elongatedopening, one of the plate members abutting against one of the side railsand the other plate member attached to the side rail, at least one ofthe plate members defining an aperture, the cavity having a pair ofparallel side walls and a pair of parallel longitudinal walls extendingperpendicularly in relation to the side walls; a slide plate mountedwithin the cavity and having a concave distal end abutting one end ofthe pulley; and a thumb wheel having a portion received in the aperturedefined by at least one of the plate members for longitudinallyadvancing the slide plate and one end of the pulley by a selectdistance.
 20. The device of claim 19 wherein the pulley adjoins theslide plate and an endless conveyor belt is trained over the pulley, theconveyor belt providing an upper conveyor surface that is constant inlength.
 21. The device of claim 19 further including another devicemounted to the conveyor for selectively and independently positioningthe pulley.